Well cementing device with jet recycling



March 1, 1955 A. B. HILDEBRANDT 2,703,

WELL CEMENTING DEVICE WITH JET RECYCLING Filed ma ze} 1955 ALEXANDER B.HILDEBRANDT INVENTOR BY ATTORNEY United States Patent WELL CEMENTINGDEVICE WITH JET RECYCLING Alexander B. Hildebrandt, Tulsa, Okla.,assignor to Standard Oil Development Company, a corporation of DelawareThis invention concerns an improved method and apparatus applicable tothe practice of cementing casings and liners and similar tubular membersin well bores. More particularly the invention relates to improvementsin the displacement of drilling mud from the bore hole annulus adjacenta casing within a well bore whereby a more eflicient cement job can beobtained.

In the course of drilling and completing an oil well it is commonpractice to insert one or more strings of casing into the well and tocement selected sections of the casing in place in order to preventundesirable fluids such as water from entering the producing formationfrom other strata above or below the producing formation. The mostcommon practice for cementing casing in the well consists in circulatinga quantity of cement down through the casing and out into the annulusbehind the casing where the cement is then allowed to set. One of theserious problems encountered in oil well cementing is that of obtainingeffective displacement of drilling mud by cement so as to produce areliable fluid-tight seal. To solve this problem there has beendeveloped a socalled jetting shoe which directs the cement slurry outthrough the orifices in the shoe to impinge against the walls of thebore hole and thereby remove the mud cake. However such equipment stillleaves much to be desired in the way of efficient displacement of all ofthe drilling mud from the annulus and from the borehole walls. It isgenerally recognized that the most important section of a string ofcasing to be cemented in a well is the lower 20 or 30 feet. If suitablemeans can be provided that will efliciently mix or displace all of themud in this sectioh of the well with cement the chances are very greatthat a reliable cementing operation will result.

It is an object of the present invention to provide a cementing methodand a device that will ensure the eflicient displacement of all of thedrilling mud from the walls of the bore hole adjacent the lower end ofthe casing and the efiicient mixing of the mud with cement so as toobtain a homogeneous mixture that will result in a better cementingoperation.

In accordance with the present invention an etncient flushing and mixingaction is provided by means of a special casing section having a nozzleassembly that exerts an aspirating effect which will cause a portion ofthe stream of cement rising in the annulus at the lower end of thecasing to be recycled back through the special casing section to mixwith fresh cement passing down through the casing.

The nature and objects of this invention will be readily appreciatedwhen reference is made to the accompanying drawing in which the singlefigure depicts, in sectional elevation, the special casing section ofthis invention in position in a bore hole.

Referring to the figure in particular, a special casing section 11 isshown in position in the bore hole 9. Casing section 11 is adapted to beattached to the lower end of conventional casing by means of the threadsprovided. Attached to the lower end of the casing section is aconventional cementing shoe 12. Also positioned within the upper portionofthe special easing section is a conventional cementing float valveassembly comprising a valve seat 13 and a float valve 14 which isnormally urged against the seat by means of spring 15 held by supportmember 16. As in conventional cementing equipment the flow valveassembly is constructed of a drillable material, such as a magnesium oraluminum alloy, or similar material.

Positioned within the lower portion of the casing section 11 is a nozzleassembly that constitutes the improvement provided by the presentinvention. A primary nozzle body 18 having a nozzle opening 19 and asecondary nozzle body 21 providing a central nozzle or passageway 22,which may also be designated a mixing chamber, constitute two elementsof the nozzle assembly. It will be noted that the second nozzle body ispositioned a spaced distance below the first nozzle body and at leastone port 26 is provided in the wall of the casing 11 in the area betweenthe two nozzle bodies.

The lower end of the second nozzle body 21 flares outwardly and ispositioned a fixed distance above the top of the shoe member 12 whichhas an upper contour matching that of the lower end of the second nozzlebody so as to define a chamber 23 therebetween. At least one port 24 isprovided in the wall of the casing member 11 to furnish fluid accessbetween chamber 23 and the bore hole annulus. Nozzle body members 18 and21 as well as shoe 12 are constructed of drillable material such as amagnesium or aluminum alloy, a phenolic plastic, a concrete aggregate orthe like so that when the cementing operation has been completed theinside of the easing may be drilled out as in conventional cementingpractice.

In utilizing the device of this invention it is attached to the lowerend of a string of casing and floated into place as in conventionalcementing practice. Then a quantity of cement is circulated down throughthe casing past the conventional float valve, through the primary nozzleopening 19 into the mixing chamber 22, out through the side ports 24 andthe cementing shoe port 25 and up through the bore hole annulus. inpassing through the primary nozzle opening 19 the stream of cement isconverted into a high velocity jetted stream of fluid. In other wordsthe nozzle by providing a substantial pressure drop converts the fluidpumping pressure exerted on the cement into velocity energy. The jettedstream of cement in passing from the primary nozzle opening into thesecondary nozzle or mixing chamber 22 creates an aspirating effect inthe vicinity of ports 26 so that fluid is drawn in through ports 26 fromthe bore hole annulus. Thus in effect the nozzle assembly serves as ajet pump. The nozzle assembly may be so designed that for each volume offluid that passes down through the primary nozzle two volumes of fluidwill be drawn in through the aspirating ports 26. Thus for a givenquantity of fluid Q being pumped down through the casing three timesthis volume of fluid, i. c. three times Q will flow up the bore holeannulus in the region between the cementing shoe and the aspiratingports 26. It will thus be seen that the fluid moving up this portion ofthe annulus will be travelling at a high velocity which will ensure thatthe mud cake clinging to the walls of the bore hole will be efiicientlyremoved therefrom. Also in view of the aspirating and mixing eifect aconsiderable quantity of cement and drilling mud will be recycledthrough the assembly a large number of times for a given quantity ofcement that is pumped down through the casing. Thus by the time all ofthe cement has been placed in position a homogeneous mixture of cementand residual mud will have been obtained so that when:l the cement setsup a fluid tight seal will be obtaine It is to be understood that thespecific embodiments of the invention described herein are by way ofexample and that the invention isnot to be limited thereto. The truescope of the invention is defined by the appended claims.

What is claimed is:

1. A device for improving the operation of cementing casing intoposition in a well bore comprising a casing section, a first nozzle bodypositioned within the casing section and providing therein a downwardlydirected fluid jet nozzle, and a second nozzle body positioned withinthe said casing section a spaced distance below said first nozzle bodyand providing within the casing a second nozzle passageway in generalalignment with said 0 first nozzle, said casing section having at leastone side port between the first and second nozzle bodies and at leastone opening below the second nozzle passageway and communicatingtherewith.

2. A device as defined by claim 1 including a cementing shoe on thelower end of the casing section and at least one side port in the casingsection above the said shoe, said last named port communicating with thelower termination of said second nozzle passageway.

UNITED STATES PATENTS Le Flore June 4, 1929 OLeary et al. May 3, 1938Brown Oct. 23, 1951

